Rotax 582 getting air in the cooling system

25 posts in this topic

Posted

Hi all,

I have recently installed a used 582 to replace the 532 that was on my Avid. I have had cooling problems since. The last several test runs of the engine on the ground with cowling off show it running fine and temps on the gauge are in the safe range but when I shut the engine down I get a long stream of air bubbles from the steam return line from the water pump back to the coolant header tank/cap. I have tried carefully removing all air from the system when filling it. I have run it briefly with the cap off and topped off with coolant to make sure any extra trapped air could escape. I never had these issues with the 532 which used the same radiator. I just changed the cylinder o-rings in the head in case I had a compression leak there into the water jacket but that made no difference. The rotary valve oil remains clean and at a constant level so no leaks there. There were no visible cracks in the cylinder head. Has the 582 ever had issues with cracks? I don't have any external leaks. Is there anything else that could be bringing air into my cooling system?

Any ideas would be greatly appreciated. I am grounded until I can figure this out.

Thanks,
Dan LaFon

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Posted

sometimes I have to burp my cooling system after draining it. You get a bubble that just won't come out.Take the radiator cap off and lift the tail as high as you can. might help or not, but it doesn't cost any thing.

 

  Jim

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Posted

Dan try lifting the tail of the plane so the air that is trapped in the back of the motor can escape. You may have to raise and lower the tail a few time to get all the air out of the system. Hope this helps

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Posted

I didn't see jims post before my reply,

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Posted

Thanks for the replies. I burp every time I refill the cooling system. I had the plane leveled with the tail wheel sitting on a bucket trying to get the last bit of air out of the water pump. The 532 was plumbed the same way and I never had these issues with it. This time I burped then fired up the engine until warm and shut down. There was quite a bit more air coming out of the water pump steam fitting. I topped off the coolant and repeated this process 3-4 times and each time I still get a significant amount of air bubbles coming out of the steam line at the water pump. I am thinking about pulling the head and having it checked for cracks.

 

Thanks,

Dan

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Posted

Dan we had the same issue on my dads kf we had to raise the tail really high with the cap off , it's easyer with two people

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Posted

The engine is inverted on the Avid so the air is not trapped in the cylinder head. It comes through the water pump and my radiator cap is mounted forward next to the gear box.

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Posted

Did you get it resolved?

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Posted

any updates?

 

I recently had and issue where a slow water leak at a fitting going into the radiator allowed air into the system and an air bubble got stuck, upon taxing up to the runway the temp gauge came up real quick stem started to blow and well lets just say it was an exciting mess and I'm glad it happened before takeoff. long story short I had to pull the small plug that goes into the water pump housing removed the fill cap and after filling as much would go in I picked the tail up in the air as high as I could get it shook it a couple times and set it back down. after doing this process a couple times and starting the engine with the plug and cap still off eventually the air burped out and water started coming out of the water pump port. I plugged it back up filled it once again and all has been good ever since. this plug can be replaced with a small hose barb and plumbed back to the fill neck. If anyone has a part number for that little fitting I would sure love to know what it is. I've seen them installed on a friends Avid but have not been able to find the right barb anywhere. 

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Posted

I am still working on this one. It is possible that my old 532 did the same thing but I never noticed because I had a solid line. I only noticed on the newer 582 when I substituted a translucent line from the water pump to the coolant tank (engine inverted) where I could see the air bubbles. I have changed my plumbing around a bit and will see if that works. The other possibility is the system is pulling back air from the coolant overflow line when the engine shuts down. I have an hour or so of ground run time on the new plumbing with no overheats so I will give it a try in the air flying circles over the runway.

 

Might be able to find the barb fitting at a hobby shop. The threads are small and they are tough to find. I just happened to have a few.

 

Dan

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Posted

I am pretty sure its a metric thread.  I ended up tapping mine out so I could screw a standard one from the auto parts store in it when I twisted mine off.

 

:BC:

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Posted

This might be way different but I do know if fuel lines if you install a few sharp 90 Degree fittings they create alot of air bubbles,

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Posted (edited)

This might be way different but I do know if fuel lines if you install a few sharp 90 Degree fittings they create alot of air bubbles,

Maybe cavitation causing those air bubbles? I have only 2 90 degree fittings in my system other than the inlet and outlet of the Kitfox style radiator. My hangar mate has several 90's in his system and he does not seem to have the problem as far as we know, although he does not have a clear line for the steam return. I guess it could be super heated coolant when passing around the exhaust ports? Not sure what the temp of the liquid is around there. On the Avid the temp sender is all the way at the lowest point in the system since the engine is inverted. Didn't get to fly last weekend due to a leak in the coolant tank that I had to modify. Hopefully this weekend if the weather isn't too bad.

 

Dan

Edited by dav8or

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Posted

A blown head gasket can inject air into the cooling system.

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Posted

The automotive channel of my brain indicates a failed head gasket would show signs of a coolant leak on the outside of the engine. If only leaking internally, I think engine performance would suffer.

$.02

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Posted

I had a Honda Accord (total piece of junk, never again!) that regularly blew a head gasket with internal leakage only.  It was fairly obvious, the engine would run, but it suddenly turned into a steam engine with a nice cloud following me wherever I went......

Mark

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Posted

Rotax 532/582 uses O-rings as the seal between the water jacket and the cylinder with another type of o-ring to seal the head to the water jacket. My o-rings were still useable but I replaced them anyway with a set from JBM industries. Their O-rings are just slightly larger is material thickness which I think will help the seal. If the cylinder o-rings were leaking I would expect to see oily residue in the coolant which I have never seen and I have drained it numerous times in troubleshooting. I also do not have any signs of steam in the exhaust.

 

These are good thoughts but have already been checked.

 

Thanks,

Dan

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Posted

regardless of where the air comes from, if you have a hose bent up and down again, it will develop air, wonder if the complete water line keeps strait all along and the higher point is the bottle?

 

Regards

Dimi3

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Posted

regardless of where the air comes from, if you have a hose bent up and down again, it will develop air, wonder if the complete water line keeps strait all along and the higher point is the bottle?

 

Regards

Dimi3

 

That gives me a great idea for modifying my coolant recovery tank to help remove the air from the system.

 

Thanks,

Dan

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Posted

I fought it on mine. Turned out to be a bad head that was machined poorly and causing some air in the system and occasionally an overheat at odd times. Also, double check that at some point you didn't do a bone head trick like some dummy I know and run the bleed line from the water pump to the coolant recovery bottle... this does not work well and defeats the pressure cap on the radiator. I fought this for a couple months before I stepped back, looked at what I had done at the last engine swap and I then kicked my own ass for being so stupid.. even though I had checked those lines 100 times I still did it wrong.

:BC:

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Posted (edited)

Yep!

Many times I have looked at a problem again and again in a program or web page while very frustrated. After a period of time :handjob: why didn't you see that 3 days ago? :nutkick:

Edited by KFfan
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Posted

Wondering if I got air in my system causing my issues. I flew it for 10 hrs after changing my cooling set up with no issues until today.

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Posted

Yep!

Many times I have looked at a problem again and again in a program or web page while very frustrated. After a period of time :handjob: why didn't you see that 3 days ago? :nutkick:

+1 on this.  Sometimes the best way to solve a problem is to stop working on it and walk away.  I can't count the number of engineering challenges met or bugs fixed quickly after giving up and coming back hours later or the next day with a fresh perspective.

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Posted

Do that make an adapter to reduce from an automotive style pressure tester?

I had no trouble at all with mine. :ph34r:

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Posted

I never replied back to this post that I had an issue with a radiator cap. I replaced the cap and pretty much solved the problem. Also instead of modifying my existing recovery bottle I found a coolant recovery tank from a Polaris something or other that has the recovery line connection at the bottom of the tank so when mounted properly it will automatically bleed any air that reaches the radiator cap from the system. I also had a thermostat that was 20° too hot which also caused problems. (crazy part numbers that were only 1 digit off)

I flew through the hottest months of summer here with OAT as high as 98° and the coolant temp never hit 180° in a steep climb out.

Dan

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